Energy-saving production of CaO- Al₂O₃-SiO₂ glass-ceramic using feldspar, calcium carbonate, and calcium fluoride

Abstract In this study, the production of CaO-Al 2 O 3 -SiO 2 glass-ceramics using 40 wt% calcium carbonate, 60 wt% feldspar, and 0–3 wt% CaF 2 as a nucleating agent was investigated. The samples were melted at 1360 °C, cooled to 500 °C, and crystallized at 950 °C. FTIR analysis showed that CaF 2 depolymerizes the glass network, increasing the NBO/T ratio from 0.708 with no CaF 2 to 0.875 with 2 wt% CaF 2 . XRD revealed the formation of albite and wollastonite in the sample containing no CaF 2 , with Ca 4 Al 2 O 6 F 2 forming in the samples containing CaF 2 , increasing crystallinity from 81% (no CaF 2 ) to 95% (2 wt% CaF 2 ). SEM and EDX confirmed a transition to a fine-grained structure in the sample containing 2 wt% CaF 2 . The addition of 2 wt% CaF 2 exhibited optimal properties, i.e., density (2.72 g cm −3 ), Vickers hardness (486 HV), and low water absorption (0.39%). However, 3 wt% CaF 2 reduced properties due to grain growth and porosity.